Does gabapentin cause weight gain?

Yes, it has the potential of causing weight gain in a small number of people:
"Metabolic
Common (1% to 10% of users): Weight gain, hyperglycemia"

Yes it does and happens rather fast. If you're able to exercise and stay active it should help shed the pounds

Yes, it does. I've been on it for several years for anxiety. By the time you realize you're gaining the weight, you can't get off of it. I would like to taper down slowly, but I know I'd still have anxiety. My main question is, will the weight come back off. I've gained about 30 lbs.

If you just started it and don't need it that bad, I'd say, don't take it.

Yes! Unfortunately I'm carrying +5-7#'s. Happened really fast after starting Gab. Like 3-6 days. Def less than a week that I noticed the additional pounds. I weigh myself religiously, everyday so I'm positive I can blame it on the Gab dose. Not to mention my Rheumatologist confirmed as well as the Rx leaflet. The Gab dose I'm on does help, though not totally, with my post-op neuropathy from low back all the way to my toes. With the small amount of extra weight I'm carrying, I'm not interested in discontinuing the medication.
Good luck my friend